Archive for May, 2012

The spring songbird migration is winding down, here is Davis.  For the last month, thousands of songbirds have been flowing through central California on their way to their breeding grounds to the north and east.  However, now the flow has slowed, and just the last few migrants are still moving toward their final destinations.  My wife and I went birding along Putah Creek, which runs along one edge of Davis, to see if we could find some of these late-moving birds.  We did see two Yellow Warblers, a Warbling Vireo and a Western Tanager, but those were the only migratory passerines that crossed our path.  The Golden-crowned Sparrows have all left as have the big numbers of American Crows.  On the other hand, the Swainson’s Hawks, Western Kingbirds and Ash-throated Flycatchers are all settled down and nesting.  And so begins the breeding season!  (To think that some people say that central California does not have seasons!)

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A few months ago I read a paper titled “Behavioral Ecology Under Threat” by two researchers (Tim Caro and Paul Sherman (2011)) who wanted to examine what the study of behavior could do for conservation.  It is a worthy goal, and the benefits to each area of study from the other seems to be largely overlooked by many in these fields.  My favorite part of this paper was a list that the authors compiled of things behavioral ecologists could do to aid in the conservation of the natural world.  They divided the list into general areas of ideas.  They do not suggest that any one person do everything on the whole list, but they do recommend people to think about the whole list and do as many as they reasonably can.  As I read their list, it occurred to me that it did not just apply to behavioral ecologists, but to anyone who is concerned about health and preservation of the ecosystems in which we live.  For this reason, I am sharing the list from Caro and Sherman (2011), in edited form, here with you.  The complete list can be found in Box 3 of their paper.  As you read over this list, some of the items will apply to each person differently.  As they do, I am recommending that each of us think about the whole list, but don’t think that any one person will have to do everything, just as much as they reasonably can.


1) Specifically gather data to address the conservation and management of a species of interest and its habitat.

2) Contact local, state, and national wildlife officials and offer assistance.

3) Work with local reserve officials in a practical sense such as volunteering on clean-up days.


1) Contact local middle- and high-school superintendents, biology department heads, and teachers to see if you can give classroom presentations of science, biology or conservation.

2) Contact national and regional conservation organizations (The Nature Conservancy, The Audubon Society, etc.) and offer to give presentations or lead nature walks.

3) Help raise funds for science be it in the form of local parks, conservation NGOs, or wildlife education organizations.


1) Acquaint local politicians with the unique habitats and organisms that are found in their home districts., and provide information that can be used to make sound policies.

2) Lobby granting organizations for new research grants that will provide data that could aid in the conservation of wildlife habitats.


1) Get involved in regional, national, and international attempts to save a species or taxa that is of interest to you.

2) Network with others who share your concerns and join, or create, a committee that will develop species or habitat conservation plans.

3) Set up an endowment, however small, that is dedicated to awarding funds to researchers who specifically incorporate conservation into their work.

4) Write blog posts or newspaper or magazine articles about conservation issues and what biologists, and others, can do to preserve the natural world for future generations.

So, what are you doing?

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I came across my first family group of Bushtits of the year, today.  The group was comprised of what looked like three adults, which were probably the mated pair and one nest helper, and four young birds.  Bushtits are one of a number of species that include nest helpers in their reproductive strategy.  These helpers are usually young from the previous year that return to aid their parents.  Young birds that fledge from a nest early in the year also sometimes stay to act as helpers as their parents raise a second brood of young.  Since this family group that I found is so early I would not be surprised if the adults attempted a second brood.

A number of ideas about why young birds help raise their siblings are floating around.  One is that the young birds are getting valuable experience in raising babies, so that they will have better success when they do eventually go off by themselves.  Another idea is that the baby birds grow faster, and so fledge earlier, when there are more helpers to feed them.  A related idea has to do with what is called inclusive fitness.  This hypothesis says that the more individuals that carry a copy of a particular gene, the better, so helping relatives survive is actually a good strategy for preserving your own genes.  This is especially true if the individuals in question are close relatives, such as siblings, because there is a lot of shared genetic information.  A further idea is that good nesting territories are few and far between, so the helpers return to their parents territory and stay around in the hope of inheriting that nesting territory if and when their parents die or breed elsewhere.  This seems particularly possible in cavity nesting birds for which cavities have been shown to be a limiting factor in reproduction.  All these hypotheses seem reasonable, and they are not necessarily mutually exclusive, but few have been really well examined!  This seems to be an area that is ripe for some observations and experiments that might yield really interesting results.

So, who wants to put up a bunch of bird boxes and see what happens?

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Birds around Davis are in high nesting gear, right now, and along with nest building comes conflicts over territories and mates.  These conflicts can be sneaking stealth raids, small border skirmishes, or fully pitched battles with the combatants hitting hard and fast.  I have witnessed several such battles just in the last few days.  The first was a contest between two male House Sparrows.  They were locked, bill to bill, on the ground rolling over each other as each pummeled the other with its wings.  This wrestling match went on for several minutes and the fact that I approached to within 10 feet or so did not seem to merit any form of acknowledgement.  Finally, one broke away from the others grasp and fled up into the low branches of a nearby tree.  It was immediately pursued by the other who drove the fleeing looser out of the area  entirely.  The winner then flew to a female who had been sitting in tree watching the whole conflict and deciding which male was the worthy mate.

A second vigorous battle I watched was between two male Anna’s Hummingbirds.  This struggle was all aerial!  No fighter pilots in the world have the ability to match what these two birds could do!  Like the House Sparrows, these hummingbirds were locked in a wrestling match, but theirs’ was a wrestling match in three dimensions as they tumbled over and over each other through the air.  Then they would break apart, and one would tail chase the other until they met again and battle was rejoined.  The speed of the whole thing was also quite impressive.  Their combat covered a whole field and in only a matter of 30 seconds or less the conflict was over.  The winner landed in the top of a bush and started bugling his victory at the top of his lungs, and the looser slipped away to try his luck elsewhere.

The last battle of the past week was directly over the quad on the U.C. Davis campus.  It involved four Swainson’s Hawks that were engaged in a bit of a territorial dispute.  Two if the birds, presumably a pair, were very aggressively chasing the other two, also presumably a pair.  The chase twisted and turned through space with the birds diving on each other repeatedly.  One such dive was done with such vigor that it sent the receiver crashing into the top of one of the oak trees that line the quad!  Finally, the resident pair convinced the interlopers to move on.  What really surprised me about this particular battle was that, at least from what I could tell, none of the 50 or 60 people milling about the quad noticed!

So, all in all, a pretty dramatic time here in central California.

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Birds striking windows is rather common and accounts for a lot of bird moralities each year.  I often get asked what one should do if they find a bird that has struck a window.  Well, yesterday, at my mom’s house, a Warbling Vireo hit one of the windows, and this prompted me to provide a little information on what to do.  The vireo was quite stunned, sitting on the deck and breathing very heavily.  To know how stressed a songbird is, there are a few warning signs.  The three most common signs are fluffed feathers (when the bird raises their feathers up away from their skin), labored breathing (sometimes it can get so labored that their whole body heaves with each breath), and closing of the eyes.  If a bird is found that shows any of these signs, the best course of action is to place the bird in a dark, quite, warm place.  Whatever the container is used, make sure that air can circulate through it.  Birds seem to recover from the stress of an impact best when they are left in such a setting for 15 to 20 minutes.

The reasoning for this kind of treatment is as follows.  Birds are highly visually sensitive, that they can be overstimulated by a lot of visual activity.  If they are already stressed from an injury, this extra input can be more then they can easily deal with, so being in the dark seems to let birds lower their stress levels.  This is why it is important to keep the bird in a dark place.  This principal is why falconers use hood on their birds.  By limiting the amount of visual stimuli, they can keep their raptors calm.  While birds a mostly visually sensitive animals, they also have fine hearing, and keeping their environment quite when they are recovering is another way to reduce the level of stress in a bird.  Finally, birds have a significantly higher metabolism than humans and have a higher basal temperature.  When they are highly stressed, they seem to loose some of the ability to regulate their own temperature and so cool off, which is bad, and which is why a warm place is so important.

I have had very good success with this technique in many situations (including when the warmest place available was in my shirt), and it worked for the Warbling Vireo.  After about 20 minutes, it was recovered enough to fly away go back to its insect eating life.  Hopefully it will remember to be more careful and not run into windows any more.

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Salsify (genus Tragopogon) is a fairly common plant all around Davis, CA.  It grows in grassy fields and on roadsides as a low cluster of leaves for its first year, and then plants grow to a height of about a meter in the spring of their second year making them biennials.  They are all tall now, and have just blossomed.  The synchrony of flowering was very impressive.  For about one week all the salisfy plants had beautiful, purple flowers at their tops (see photo below).  Then, seemingly all on the same day, all the flowers closed.  This high level of flowering synchrony helps ensure that all the plants get pollinated by increasing the odds that any pollinator that visits a salsify flower will have just recently visited a different salsify flower and so carrying appropriate pollen.  But how do the plants know?  How do they all coordinate so effectively?

The genus Tragopogon has about 140 species.  They were originally native to Eurasia, but have been introduced to North America and Australia and have spread widely there.  They have a large taproot that is usually 10 to 20 cm long and resembles a pale carrot, and which is commonly eaten in some parts of the world.  I have tried it on a couple of occasion and found it to be rather good once cooked thoroughly and mashed like potatoes.  After the flower dies, they produce a large head of wind-dispersed seeds that looks like a huge dandelion head.  They really are quite attractive plants!

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